The Chile midfielder has had an impressive World Cup despite a lack of fitness, but has been a United target for far longer. The English club first began to properly enquire about the 27-year-old in January.

Sources state United have picked up their interest in the player over the past few weeks, and Vidal himself is understood to be open to the idea. Arsenal are also seen to be in the running.

Juventus, however, remain unwilling to sell their star player, while any negotiations are likely to be complicated as it will take an offer of over 45 million pounds to even make the Italian side consider the possibility.

Vidal would represent a huge coup for United, given that he would be both the "marquee name" that the hierarchy crave, but also see a key position filled.

Around 60 million pounds has already been paid out on Luke Shaw and Ander Herrera, but manager Louis van Gaal is keen to bring in at least one midfielder and one centre-half.

It is expected that a deal for Thomas Vermaelen will be struck with Arsenal in the next few weeks, although both a fee and a medical have to be finalised, with the Belgium centre-half recently struggling with injury.

As he seeks to strengthen his United backline, Van Gaal wants a defender with Premier League experience but also mobility -- and the club are still expected to pursue their interest in Borussia Dortmund's Mats Hummels.

Van Gaal would also like to bring in his Netherlands midfielder Nigel de Jong, and there remains tentative interest in Bayern Munich's Bastian Schweinsteiger.

Sources also state that Javier Hernandez will be allowed to leave the club, providing a suitable offer comes in. The Mexican has seen his playing opportunities increasingly limited.